Two related research projects on drug use among Native American young people will be done--a longitudinal study and a cross-sectional survey. The longitudinal study will determine how drug use changes over time. Approximately 1800 young people from three large, geographically distinct tribal groups in grades four through twelve will be surveyed during the Spring semester of 1981 and later during the Fall semester of 1982. Each drug use type (for example, those who use both inhalants and alcohol heavily in the 7th grade) will be followed up to determine what their patterns of drug use are 2 1/2 years later. A wide range of factors will be assessed to identify characteristics that predict later consequences, i.e., increased drug involvement or later avoidance including: age of first use, type and extent of early drug use, family and peer influences, reasons for using drugs, identification with Native American culture, anxiety/unhappiness, attitudes to deviance, etc. The cross-sectional study will be in in-depth examination of inhalant and PCP epidemiology, since increases in both are expected during the next three years. Geographic isolation and cultural characteristics of at least 12 tribal groups sampled over three years will be examined to test hypotheses about how drug use spreads across reservations. PCP and inhalant use will be examined in the context of other drug use and correlated with the above list of factors to determine what attitudes and social surrounding characteristics relate to their use. The total N for both studies will be approximately 5120.